Gap-free Neural Circuits: From Sensory Input to Motor Output

A 10-day course offered during MIT IAP 2013

Time & Place: January 7-18, Monday-Friday, 4-5:30p, Room 46-3015

Sign-up: Please use the sign-up form to register for the class.

Course description: Why do people act the way that they do? How sensory input alters the behavioral output of living organisms is a fascinating question in neuroscience. While this is difficult to study in a gap-free manner at the cellular level in mammals, gap-free neural circuits have been identified and their signal transformation properties characterized in simpler organisms. On each day of this class we will discuss a single neural circuit that has been worked out at the cellular level, including how each neuron in the circuit transforms the incoming physiological signal using specific molecules. Circuits will be derived from primary experimental data. We will focus on circuits for which the neurons that sense the stimuli are known, the interneurons are known, and the motor neurons controlling muscle contraction and the resulting behavior are known. Circuits will be drawn from several invertebrate organisms, including the genetic organisms C. elegans and Drosophila, as well as the locust, crayfish and cricket. After this class students will have a precise understanding of several different neural circuits as well as the methods used to identify and analyze these circuits. By providing several examples of real neural circuits, principles for how circuits function in general may become apparent. Students, post-docs and professors welcome.


  • Tatsuo Okubo: Grad student in the Fee lab, where he studies song-learning in the zebra finch, using electrophysiology, lesions and quantitative behavioral analysis.
  • Nikhil Bhatla: Grad student in the Horvitz lab, where he studies the C. elegans nematode's response to light, using imaging, ablations, genetics and behavior assays.

    Contact: &

    * is required reading              

    Week 1:
    Jan 7 Introduction (Tots & Nikhil) - Notes - Circuit analysis rubric - Slides
    Overview of course, philosophy and motivation, electrophysiology and imaging, circuit analysis, and other methods.
    Olsen & Wilson 2008 (*)
    Jan 8 Crayfish escape (Tots) - Slides - Video of crayfish escape
    Fictive behavior, command neuron, local and distributed computation, rectifying electrical synapse for coincidence detection, presynaptic inhbition, proximal vs. distal dendritic inhibition.
    Olson & Krasne 1981 (*)
    Edwards..Krasne 1999
    Jan 9 Worm: Touch-induced locomotion (Nikhil) - Notes - Slides - Slides+videos
    C. elegans-specific neural signaling, connectome-motivated hypothesis generation, ordering neurons into a circuit, convergent excitatory circuit, parallel disinhibitory circuit.
    Piggott..Xu 2011 (*)
    Chalfie..Brenner 1985
    Li..Xu 2011
    Kawano..Zhen 2011
    Jan 10 Locust flight (Tots) - Slides
    Tethered flight, central pattern generators (CPGs), proprioceptive feedback, neural system for achieving stable flight, interneurons important for phase-coupling.
    Reichert..Griss 1985 (*)
    Reichert & Rowell 1986
    Robertson & Pearson 1985
    Jan 11 Worm: Light-induced pump stop (Nikhil) - Notes (partial) - Slides (partial)
    Neural network islands, nervous system as modulatory, redundant control circuits, temporal tiling of circuit function.
    Avery & Horvitz 1989 (*)
    Ward..Xu 2008
    Edwards..Miller 2008
    Liu..Xu 2010
    Week 2:
    Jan 14 Worm: Olfaction & chemotaxis (Nikhil) - Notes - Slides - Slides+videos
    Sensory processing of food odors, motor control of turning, local search for food, repetitive sign inversion in a linear chain.
    Chalasani..Bargmann 2007 (*)
    Kocabas..Ramanathan 2012 (*)
    Bargmann..Horvitz 1993
    Jan 15 Fly mating decision (Tots) - Slides
    Behavioral effect of pheromones, circuit tracing using PA-GFP, demonstration of functional connectivity, triggering behavior using artificially activated neurons.
    Ruta..Axel 2010 (*)
    Ha & Smith 2006
    Kurtovic..Dickson 2007
    Dickson 2008
    Jan 16 Worm mating (Nikhil) - Notes - Slides - Slides+videos
    Neural control of male attraction to hermaphrodite pheromones, retention with mechanical stimuli, mating motor program: finding, stroking, vulva locating, penetrating, ejaculation; independent modules that form a motor sequence.
    Liu & Sternberg 1995 (*)
    Garcia..Sternberg 2001
    Barr & Garcia 2006
    Loer & Kenyon 1993
    Jan 17 Cricket mating (Tots) - Notes - Slides
    Biomechanics of song production in the male, corollary discharge, sound localization and pattern recognition in the female.
    Poulet & Hedwig 2006 (*)
    Hedwig 2006
    Jan 18 Conclusion (Tots & Nikhil)
    Review of circuit analysis methods, final circuit principles, connection to mammals.


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